This invention relates to means for selecting needles of a knitting machine, especially a hand knitting machine, according to a program, and more particularly to a system for providing electric signals representative of data for needle selection in a course of knitting according to a program. More specifically, the present invention relates to and is an improvement of the program providing means disclosed in patent application Ser. No. 686,380 in U.S.A. entitled "A method and apparatus of selecting needles of a knitting machine", and assigned to the assignee of the instant patent application.
The selection of knitting needles is required to achieve different knitting patterns and weaving effects. Since the manual selection of the knitting needles is both difficult and time consuming, and makes the operation of a knitting machine considerably more difficult, automatic selection of knitting needles was undertaken by which means the knitting machine was greatly simplified, and without any special act on the part of the person operating the machine, facilitated knitting of very diverse patterns.
For this purpose, several automatic needle selection mechanisms have been already proposed which employ electromagnetic means such as an electromagnet which may preferably be mounted on a carriage and is adapted to be selectively energized in accordance with a needle selection program. A needle selection program is provided by a program providing means which comprises a program carrier having a program of a pattern to be knitted thereon and is adapted to read the program to provide electric signals representative of data for needle selection. The program carrier may be a well-known punch card or a program sheet made of paper or plastics material upon which a pattern or design has been drawn in continuous contour lines or by colored areas.
In a hand-operated home knitting machine, it is required to mount a program carrier on the needle bed or the carriage so as to leave it in the eyesight of a machine operator so that she can visually confirm at any time the program she is currently knitting. Such confirmation is absolutely necessary when corrective- re-knitting must be performed, as a result of incorrect knitting. U.S. Pat. No. 3,885,405 discloses a program providing means in which a program carrier can be inserted alongside the needle bed in an intermittently feeding card holder to be fed from line to line and is directly scanned by a reading head mounted on the carriage when the carriage traverses the program carrier. The afore-mentioned Patent Application also discloses a program providing means in which, however, a reading head is mounted alongside the needle bed for movement in a predetermined path between two end positions and adapted to be moved therebetween by the carriage itself, means being provided for releaseably accompanying the carriage with the reading head.
However, the movement of the reading head is directly related to the movement of the carriage in either of the above-described program-providing means. In scanning the program carrier, it is always necessary to traverse the carriage. Such an operation is troubesome. Further, when the reading head reads the program, there is a difference between reading during the movement in one direction and reading during the movement in the other direction, which leads to inaccurate reading. If the carriage is stopped midway or reversed and moved in the opposite direction while the reading head is traversing, the reading may be mistaken.